mineral

Calcite

Calcium Carbonate (CaCO3)

Hardness of 3 on the Mohs scale, typically white or colorless, vitreous to earthy luster, rhombohedral crystal system, perfect rhombohedral cleavage, specific gravity of approximately 2.71.

Identified July 28, 2026More mineral →

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Physical properties

Hardness of 3 on the Mohs scale, typically white or colorless, vitreous to earthy luster, rhombohedral crystal system, perfect rhombohedral cleavage, specific gravity of approximately 2.71.

Formation & geological history

Formed in sedimentary, metamorphic, and igneous environments. Most commonly found in sedimentary rocks like limestone and marble, precipitated from water rich in calcium and carbonate ions.

Uses & applications

Widely used in the construction industry for cement and lime, in agriculture to neutralize soil acidity, in the manufacture of paper, paints, and plastics, and as collector specimens.

Geological facts

Calcite exhibits strong birefringence (double refraction), meaning light passing through it is split into two rays. It is the primary constituent of limestone and marble.

Field identification & locations

Easily identified by its characteristic rhombohedral cleavage and strong effervescence (fizzing) when exposed to weak hydrochloric acid. Found worldwide in sedimentary basins and hydrothermal veins.